Author
Simone Panaro
Other affiliations: University of Genoa
Bio: Simone Panaro is an academic researcher from Istituto Italiano di Tecnologia. The author has contributed to research in topics: Plasmon & Fano resonance. The author has an hindex of 11, co-authored 21 publications receiving 399 citations. Previous affiliations of Simone Panaro include University of Genoa.
Papers
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TL;DR: A nanoassembly supporting the hybridization of an electric and magnetic plasmonic mode in Fano resonance conditions is investigated, able to generate an intense and localized magnetic hot-spot in the near-infrared spectral region.
Abstract: The possibility to develop nanosystems with appreciable magnetic response at optical frequencies has been a matter of intense study in the past few years. This aim was strongly hindered by the saturation of the magnetic response of "natural" materials beyond the THz regime. Recently, in order to overcome such limitation, it has been considered to enhance the magnetic fields through the induction of displacement currents triggered by plasmonic resonances. Here we investigate a nanoassembly supporting the hybridization of an electric and magnetic plasmonic mode in Fano resonance conditions. Taking advantage of the enhancement properties owned by such interferential resonance, we have been able to generate an intense and localized magnetic hot-spot in the near-infrared spectral region.
87 citations
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TL;DR: In this paper, a T-shaped nanoantenna trimer has been introduced as an elemental unit for the energy transfer between bright and dark modes in plasmonic nanostructures.
Abstract: The excitation of plasmonic dark modes via a radiative channel is a phenomenon strongly hindered in the subwavelength regime. Recently, for achieving this purpose it has been proposed to exploit near-field interactions between radiating (bright) modes and lossless dark modes. However, this approach unveils challenging difficulties related to the excitation of dark modes through the near-field coupling with a bright mode. Here, it is experimentally and numerically shown how symmetry breaking applied to a nanoantenna dimer can conversely induce the excitation of plasmonic resonances, which play a key role for the dark modes’ activation in more complex nanoassemblies. On the basis of this study, a T-shaped nanoantenna trimer has been introduced as an elemental unit for the energy transfer between bright and dark modes in plasmonic nanostructures. Finally, we implemented an analytical perturbative model to further investigate the plasmonic hybridization of subwavelength systems.
70 citations
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TL;DR: It is demonstrated that an enhancement of the Q/V ratio with respect to the pure LSP and DSW is obtained for SLRs with a well-defined degree of plasmon hybridization, which opens the way toward more efficient applications for the exploitation of excitonic nonlinearities in hybrid plAsmonic platforms.
Abstract: Combining localized surface plasmons (LSPs) and diffractive surface waves (DSWs) in metallic nanoparticle gratings leads to the emergence of collective hybrid plasmonic–photonic modes known as surface lattice resonances (SLRs). These show reduced losses and therefore a higher Q factor with respect to pure LSPs, at the price of larger volumes. Thus, they can constitute a flexible and efficient platform for light–matter interaction. However, it remains an open question if there is, in terms of the Q/V ratio, a sizable gain with respect to the uncoupled LSPs or DSWs. This is a fundamental point to shed light upon if such modes want to be exploited, for instance, for cavity quantum electrodynamic effects. Here, using aluminum nanoparticle square gratings with unit cells consisting of narrow-gap disk dimers—a geometry featuring a very small modal volume—we demonstrate that an enhancement of the Q/V ratio with respect to the pure LSP and DSW is obtained for SLRs with a well-defined degree of plasmon hybridizati...
63 citations
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TL;DR: The role of plasmonic nanoshells, embedded within a ultrathin microcrystalline silicon solar cell, in enhancing broadband light trapping capability of the cell and, at the same time, to reduce the parasitic loss is investigated.
Abstract: With the objective to conceive a plasmonic solar cell with enhanced photocurrent, we investigate the role of plasmonic nanoshells, embedded within a ultrathin microcrystalline silicon solar cell, in enhancing broadband light trapping capability of the cell and, at the same time, to reduce the parasitic loss. The thickness of the considered microcrystalline silicon (μc-Si) layer is only ~1/6 of conventional μc-Si based solar cells while the plasmonic nanoshells are formed by a combination of silica and gold, respectively core and shell. We analyze the cell optical response by varying both the geometrical and optical parameters of the overall device. In particular, the nanoshells core radius and metal thickness, the periodicity, the incident angle of the solar radiation and its wavelength are varied in the widest meaningful ranges. We further explain the reason for the absorption enhancement by calculating the electric field distribution associated to resonances of the device. We argue that both Fabry-Perot-like and localized plasmon modes play an important role in this regard.
43 citations
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TL;DR: In this paper, a prototypical hybrid system formed by strong coupled gold hole arrays and Jaggregate molecules was investigated by using both steady-state spectroscopic method and ultrafast pump-probe approach.
Abstract: A prototypical hybrid system formed by strong coupled gold hole arrays and J-aggregate molecules is investigated by using both steady-state spectroscopic method and ultrafast pump-probe approach In particular, the plasmonic response of the device has been tuned by modifying its periodicity thus to achieve the strongest possible coupling regime It is found that in the transient absorption spectra, under upper band excitation, the bleaching signal from uncoupled J-aggregate molecules completely disappears Instead, two distinctive period dependent bleaching bands are formed, clearly fingerprint of the hybrid exciton-plasmon state The dynamics of these bands is also directly analyzed A remarkable long lifetime is found especially for the upper band, corresponding to the presence of a trap state in its transient absorption spectra under resonance excitation Such unique feature should provide a new approach to control quantum-mechanical states under coherent coupling
40 citations
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TL;DR: A reversible 2H-to-1T phase transition in a MoS2 monolayer is realized by plasmonic hot electrons, resulting in an effective shift of photoluminescence.
Abstract: A reversible 2H-to-1T phase transition in a MoS2 monolayer is realized by plasmonic hot electrons. This transition can be actively controlled by the incident light intensity, wavelength, sample areas, and perimeters, resulting in an effective shift of photoluminescence. The suggested configuration paves the way for plasmonic optoelectronic device applications of MoS2 in the future.
515 citations
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TL;DR: A first-ever in-depth description of the theoretical relationship between surface plAsmon resonance and its affecting factors, which forms the basis for active plasmon control, will be presented.
Abstract: Active plasmonics is a burgeoning and challenging subfield of plasmonics. It exploits the active control of surface plasmon resonance. In this review, a first-ever in-depth description of the theoretical relationship between surface plasmon resonance and its affecting factors, which forms the basis for active plasmon control, will be presented. Three categories of active plasmonic structures, consisting of plasmonic structures in tunable dielectric surroundings, plasmonic structures with tunable gap distances, and self-tunable plasmonic structures, will be proposed in terms of the modulation mechanism. The recent advances and current challenges for these three categories of active plasmonic structures will be discussed in detail. The flourishing development of active plasmonic structures opens access to new application fields. A significant part of this review will be devoted to the applications of active plasmonic structures in plasmonic sensing, tunable surface-enhanced Raman scattering, active plasmoni...
459 citations
03 Jan 2012
TL;DR: It is demonstrated that a plasmonic binary NOR gate, a 'universal logic gate', can be realized through cascaded OR and NOT gates in four-terminal plasMonic nanowire networks.
Abstract: Modern electronics based on semiconductors is meeting the fundamental speed limit caused by the interconnect delay and large heat generation when the sizes of components reach nanometer scale. Photons as a carrier of the information are superior to electrons in bandwidth, density, speed, and dissipation. More over, photons could carry intensity, polarization, phase, and frequency information which could break through the limitation of binary system as in electronic devices. But due to the diffraction limitation, the photonic components and devices can not be fabricated small enough to be integrated densely. Surface plasmon polariton is quanta of collective oscillations of free electrons excited by photons in metal nanostrucrures, which offers a promising way to manipulate light at the nanoscale and to realize the miniaturization of photonic devices. Hence, plasmonic circuits and devices have been proposed for some time as a potential strategy for advancing semiconductor-based computing beyond the fundamental performance limitations of electronic devices, as epitomized by Moore's law. A variety of individual plasmonic nanodevices have been intensively studied recently, but the crucial and necessary step to enable nanophotonic circuits for future information technology, namely cascade logics integrated on-chip, has not been achieved. Here we demonstrate that a nanophotonic binary logic NOR gate can be realized by cascading plasmonic OR and NOT gates in four-terminal nanowire networks. We explain the operating principle for the device based on quantum dot luminescence imaging, which reveal the interferences for different logic functions between propagating plasmon wave packets in the nanowire network in great detail. Since the NOR gate is logic complete, i.e. any Boolean logic gate can be constructed from it, our results could have a key role in defining a viable path for the development of novel subwavelength optical processor architectures.
363 citations
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TL;DR: Directional Fano resonance in silicon nanosphere dimers shows promising applications in areas such as directional nanoantenna or optical switching, opening up avenues for developing all-dielectric low-loss metamaterials or nanophotonic devices at visible wavelengths.
Abstract: Fano resonance arising from the interaction between a broad “bright” mode and a narrow “dark” mode has been widely investigated in symmetry-breaking structures made of noble metals such as plasmonic asymmetric oligomers or other well-designed nanostructures. However, Fano resonance in nanoscale all-dielectric dimers has not been experimentally demonstrated so far. We report the first experimental observation of directional Fano resonance in silicon nanosphere dimers (both homodimer and heterodimer) and clarify that the coupling between magnetic and electric dipole modes can easily generate Fano resonance in all-dielectric oligomers, distinctly differing from conventional Fano resonances based on electric responses or artificial optical magnetism. A silicon nanosphere dimer, exhibiting a strong magnetic response inside and an electric enhancement in the gap, is an excellent structure to support magnetic-based Fano scattering. Interactions between magnetic and electric dipoles can suppress backward scatteri...
197 citations
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TL;DR: This review summarizes recent experiments in which the strong coupling regime has led to new interesting results, such as the possibility of collective strong coupling between X-rays and matter excitation in a periodic array of Fe isotopes, which extends the applications of quantum optics and more efficient second-harmonic generation from the low polaritonic state.
Abstract: Resonance interaction between a molecular transition and a confined electromagnetic field can reach the coupling regime where coherent exchange of energy between light and matter becomes reversible. In this case, two new hybrid states separated in energy are formed instead of independent eigenstates, which is known as Rabi splitting. This modification of the energy spectra of the system offers new possibilities for controlled impact on various fundamental properties of coupled matter (such as the rate of chemical reactions and the conductivity of organic semiconductors). To date, the strong coupling regime has been demonstrated in many configurations under different ambient conditions. However, there is still no comprehensive approach to determining parameters for achieving the strong coupling regime for a wide range of practical applications. In this review, a detailed analysis of various systems and corresponding conditions for reaching strong coupling is carried out and their advantages and disadvantages, as well as the prospects for application, are considered. The review also summarizes recent experiments in which the strong coupling regime has led to new interesting results, such as the possibility of collective strong coupling between X-rays and matter excitation in a periodic array of Fe isotopes, which extends the applications of quantum optics; a strong amplification of the Raman scattering signal from a coupled system, which can be used in surface-enhanced and tip-enhanced Raman spectroscopy; and more efficient second-harmonic generation from the low polaritonic state, which is promising for nonlinear optics. The results reviewed demonstrate great potential for further practical applications of strong coupling in the fields of photonics (low-threshold lasers), quantum communications (switches), and biophysics (molecular fingerprinting).
166 citations